Modern Physics Letters B

In this paper, a reliable and effective local discontinuous Galerkin (LDG) scheme for numerically solving the classical Rosenau–Hyman equation with non-periodic boundary conditions has been proposed. This study employs the third-order nonlinearly stable total variation diminishing Runge–Kutta method and the LDG method, respectively, to discretize the temporal and spatial derivatives. Finally, numerical simulations are performed on various test problems and compared with the exact results as well as results produced by a few other numerical methods, to analyze the reliability and efficiency of the proposed method. The results generated, which validate the expected order of accuracy, are presented through multiple tables. In addition, several graphical representations of the problem are presented to depict the behavior of the solution.

This work is about the investigation of the flow of a micropolar nanoliquid over a stretching surface, taking into account the effects of thermal radiation, thermophoresis, and Brownian motion. The study focuses on the impact of these factors on heat and mass transfer rates, with the assumption that the Newtonian heat impact dominates. The homotropy approach is used to generate non-dimensional transformational parameters, which are then used to create a system of nonlinear differential equations. The study includes charts and tables that define transfer rates based on various parameters, and the results suggest that increased radiance levels and Nb parameters lead to improvements in heat and mass convection. The graphics used in the study are accurate and consistent with previous research in the field. Overall, this research provides insights into the complex dynamics of micropolar nanoliquid flow and the factors that impact heat and mass transfer in this system.

The main objective of this research is the explanation of the replacement of feldspar limestone imported from Spain with recycled automotive glass, in order to reduce waste and promote environmental sustainability. Details and efforts of making porcelain ceramics from local raw materials such as quartz, kaolin and glass are also given. Replacing the feldspar with reclaimed automotive glass shows the effect of the Na₂O and CaO solvents contained in the glass on the sintering and crystallization of the studied porcelain. The results showed that the added glass contributes to the reduction of the density and the acceleration of the sintering process, by occupying the sites of the open spaces, observed in the samples not containing feldspars. By reaching a nonporous ratio at a temperature of 1000^∘C, the melting of the material is accelerated due to the dissolved oxides it contains, in addition to the linear shrinkage rate in samples that contain a lot of glass reaching the normal level of porcelain (about 12%) at low temperature compared to ordinary porcelain.

The microfluidic device with sharp-edge structures excited with acoustic wave has the characteristics of simple structure, easy manufacture, good bio-compatibility and fast response and has a good application prospect. In order to make full use of its driving characteristics, a scheme of microfluidic driving device with sharp-edge structures is designed in this paper, and the effect of structural parameters on its driving performance is analyzed with the finite element software COMSOL5.6. The model of sharp-edge structure in micro channel is established, and the relationship between the vibration mode and the resonant frequency and the inclined angle of sharp-edge structure is simulated. With the increase of the inclined angle of the sharp-edge structure, its resonant frequency with optimal vibration mode increases. The effects of the micro channel width, the inclined angle between the sharp-edge structure and the micro channel, and the distance between the two sharp-edge structures on the driving velocity are analyzed with the optimal vibration mode. The results show that the parameters of the sharp-edge structure and the micro channel can significantly affect the micro flow field and the driving effect of the micro fluid. As the width of the micro channel, the inclined angle between the sharp-edge structure and the micro channel, and the distance between the two sharp-edge structures decrease, the flow field in the micro channel increases. When the micro channel width is 500$\mu$m, the inclined angle between the sharp-edge structure and the micro channel is 45^∘, and the distance between the two pairs of sharp-edge structures is 150$\mu$m, the microfluidic driving effect is the best, the maximum flow rate is 458.24$\mu$m/s and the velocity fluctuation transverse along the micro channel is the smallest.

In this paper, we construct a hierarchical network generated from the Thue–Morse sequence. First, we deduce that the degree distribution of the Thue–Morse hierarchical network follows an exponential distribution. Then, we compute the degree correlations by calculating the average degree of all neighbors of nodes which have degree k, denoted $k_{nn}(k)$. By getting an accurate range of $k_{nn}(k)$, we show that $k_{nn}(k)\sim \frac{1}{2}k$ and the Thue–Morse hierarchical network is assortative. Finally, we conclude that the hierarchical networks generated from substitution sequences still have the same properties as deterministic hierarchical networks.

The thermal radiation and Fourier flux have drawn the attention of scientists and experts due to their extensive applications in the fields of medicine, manufacturing modern airplanes, water distillation, more efficient electronic devices, more efficient batteries, radiating treatment, and the textile industry. Through careful consideration of this, the mathematical investigation of natural convection and Fourier flux on the flow of energy and diffusion transmission of a body of cone and cylinder revolution, located in a saturated medium, has been described for the dual situations (flow over a cone and a cylinder). After then, the Runge–Kutta technique was used to explain the leading mechanism. Possessions of governing physical measures of local Nusselt and Sherwood numbers as well as velocity, thermal and diffusion figures are provided with support of tables and diagrams. It is motivating to declare that mass transfer rate is advanced in cone kind of revolution matched to cylinder kind of revolution with rising $N_R,N_t,Q_S$. Also, the heat transmission rate is upper in cylinder revolution equated to cone revolution.

This paper considers two-dimensional electrically conducting and incompressible ternary hybrid nanofluid flow on a stretching sheet with the convective boundary condition and heat source effect. Relevant similarity formulas are effectuated in converting the governing equations into a system of ordinary differential equations (ODEs) and are further treated numerically using the spectral quasilinearization method (SQLM), with error analysis. The prominent dimensionless parameters controlling the flow, and heat transfer characteristics are discussed. The results of this study show that Eckert number, heat source parameter, and magnetic effect boost the temperature profile. This work expected significant information for the future applications of innovative heat transfer devices, as well as a valuable reference for researchers to study flow behavior under various assumptions.

Using similarity methods with general physical assumptions and sufficient mathematical relations, researchers can obtain approximate solutions ready for experimental confirmation. Singh et al. claimed to have analyzed the second-kind self-similar motion of converging cylindrical shock waves in magnetogasdynamics. However, we found the dominated equation (11) and relevant equations of Singh et al. [Chin. Phys. Lett. 28(9) (2011) 094701] as well as the dominated equation (12) and relevant equations of Singh et al. [AIAA J. 48(11) (2010) 2523] being not correct. We show the correct mathematical derivations in details. It seems to us corresponding equations as well as illustrations by Singh et al. are of doubt due to above-mentioned issues. Our results imply the similarity exponent $\alpha$ obtained by Singh et al. will be close to that for the converging spherical shock waves.

There is intensive research by the community to improve materials for renewable energy applications such as hydrogen production, photovoltaics and light-emitting diodes. Titanium dioxide (TiO₂) is an important material where we can improve its fundamental properties, through doping aiming to form more efficient devices. Here, we use electronic structure calculations based on density function theory (DFT) to explore the effect of dopants, such as boron (B), germanium (Ge), molybdenum (Mo), and tungsten (W), on the structural and electronic properties of TiO₂. We investigated both the interstitial and the oxygen substitutional positions, and for the minimized energy optimized structures, we used hybrid DFT calculations to predict the electronic properties through the density of states, which proved costly but not as much to outweigh their advantage in accuracy. For most cases considered, the dopants reduce the theoretical bandgap of TiO₂, while gap states form. The variation of the bandgap ranges from a very small increase of 0.04eV to a significant decrease of 0.8eV, while the exact “position” of new gap states differs for each type of dopant and for its “spot” in the crystalline structure. It is proposed that these states and the change of the bandgap contribute to the significant changes in the optical and electronic properties of TiO₂ and can be beneficial to the photovoltaic and photocatalytic applications of TiO₂ and its implementation for hydrogen production.

In order to deeply investigate the dielectric and ferroelectric photovoltaic properties of BiFeO₃ (BFO) thin films, the Pt/BFO/La${}_{0.5}$Sr${}_{0.5}$CoO₃ (LSCO) heterostructure ferroelectric capacitor grown on (001) SrTiO₃ (STO) substrate is successfully fabricated by off-axis magnetron sputtering. The X-ray diffraction (XRD) and Phi scanning results show that the STO-based BFO and LSCO films are both (001) epitaxial structure. Although the BFO ferroelectric film exhibits an obvious dielectric dispersion phenomenon, a remarkable ferroelectric photovoltaic performance is obtained with open circuit voltage ($V_{\mathrm{\text{OC}}}$) of 0.38V and short-circuit current ($J_{\mathrm{\text{SC}}}$) of 0.23mA/cm², respectively. With increasing test temperatures, $V_{\mathrm{\text{OC}}}$ decreases slowly and then rapidly, while $J_{\mathrm{\text{SC}}}$ increases rapidly and then decreases. At a critical temperature of 80^∘C, the BFO ferroelectric film exhibits a faster photovoltaic response, in which the values of $V_{\mathrm{\text{OC}}}$ and $J_{\mathrm{\text{SC}}}$ are about 0.19V and 0.28mA/cm², respectively. Moreover, the energy band analysis indicates that a large work function difference ($\sim 1$eV) between LSCO and Pt leads to a strong built-in electric field in the BFO film, which is beneficial to separate the photo-generated carriers and improve ferroelectric photovoltaic effect. In all, this study not only shows that BFO is an excellent and environmentally friendly photovoltaic candidate material, but also provides a practical strategy for improving the performance of BFO ferroelectric photovoltaic devices.

The work is devoted to the study of the thermoelectric properties of solid crystal Yb_xBi${}_{2-x}$Te₃. This work presents the results of studies of the thermoelectric properties of Yb_xBi${}_{2-x}$Te₃ ($x\le 0.10$) solid solutions before and after annealing in the temperature range 300–580K. Regularities of changes in the electrical conductivity, Seebeck coefficient, and total thermal conductivity of the samples depending on the content of ytterbium (Yb) are established. Dependences of electrical conductivity, Seebeck coefficient, and the thermal conductivity on temperature for the crystal under study are plotted. Temperature curves were recorded using a Termoscan-2 low-frequency temperature recorder at a heating rate of 283K/min. Studies of conductivity $\sigma$, thermoelectric power (S) were carried out by the four-probe method at direct current in the temperature range of 300–600K. Ohmic contacts were applied using alloys. It has been established that the optimal combination of these thermoelectric characteristics is achieved for the compositions $x=0.1$, which are characterized by the maximum thermoelectric index ($ZT=0.87$) of the figure of merit in the temperature range of 420–500K after annealing at 500K for $\tau =240$h. It was revealed that the Yb_xBi${}_{2-x}$Te₃ systems under study are n-type semiconductor thermoelectric materials in the temperature range of 300–600K.

In this study, we report on the direct-current (DC) and frequency characteristics of split-gate heterostructure field-effect transistors (HFETs) with different split-gate lengths. The split-gate HFET contains two distinct operating parts, the large and the small transconductance parts. The split-gate HFET has a current cutoff frequency ($f_T$) of 814MHz and a maximum oscillation frequency ($f_{max}$) of 18.8GHz in the large transconductance part. Meanwhile, in the small transconductance part, there is a higher unilateral power gain of $f_{max}=27.7$GHz. Also, the split-gate HFET exhibits a voltage gain greater than 1 (0dB) at both DC and frequencies. Additionally, compared to the large transconductance part, the small transconductance part of the split-gate HFET presents a 53.5% reduction in DC power consumption and a larger input signal voltage range. Split-gate HFETs can be used as conventional power amplifiers in the large transconductance part and are also suitable as low-power voltage amplifiers in the small transconductance part.